Physiological insights into the role of temperature and light conditions on in vitro growth, membrane thermostability and antioxidative activity of Nardostachys jatamansi, an IUCN Red-listed critically endangered therapeutic plant

Abstract

Habitat modifications induced by rapid climate change and anthropogenic activities over the years have led to the extinction or confinement of many plant species in their geographic ranges. Temperature and light are the major determinants in controlling plant growth; each plant species having specific temperature and light requirements for their development and proper functioning of the photosynthetic activity. An efficient in vitro propagation protocol via callus-mediated organogenesis from rhizome segments has been developed for Nardostachys jatamansi (D. Don) DC. or ‘Jatamansi’, an IUCN Red-listed critically endangered plant species of immense medicinal importance. To understand the temperature and light sensitivity, and oxidative stress response of this plant, the micro-shoots were raised in vitro in the culture room (24 ± 2 °C, 50 µmol m−2 s−1 PPFD) and growth chamber (13 ± 2 °C, 850 µmol m−2 s−1 PPFD) mimicking the natural habitats. Maximum shoot regeneration (84.5%) and number of shoots (16.8 ± 0.2) per explant were observed in MS medium supplemented with 1.0 mg/l meta-Topolin and 0.5 mg/l indole acetic acid under low temperature and higher light intensity in the growth chamber. The genetic fidelity was assessed using flow cytometry and no major genetic abnormalities was observed among the regenerants. The activities of antioxidant enzymes like superoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase under same culture conditions were also recorded to have increased which revealed their active involvement against oxidative stress. On the other hand, a significant decline in these enzyme activities was observed in cultures incubated in culture room indicating impaired detoxification which could be due to their inactivation at high temperature and low light intensity. It was also observed that prolonged culture of in vitro-grown shoots in the culture room led to increased cell membrane damage, lipid peroxidation and higher endogenous H2O2 accumulation with reduced level of photosynthetic pigment contents, exhibiting severe oxidative stress. The in vitro-grown shoots were better maintained under conditions mimicking the natural conditions of growth which substantiated the understanding of survival strategies of this critically endangered plant species.